Recycling and reusing coal ash

In February 2014, more than 80 000 short t of coal ash spilled into the Dan River in Virginia, resulting in extensive clean-ups and concerns about the safety of the local drinking water. The amount of coal ash that poured into the Dan River was equal to the weight of the Washington Monument aboveground.

Every year, the more than 500 coal-fired power plants in the US produce 140 million short t of coal ash – enough to fill one million railroad cars. Millions of short tons are stored in ponds, landfills and abandoned mines, often on the same site as the coal plants that produced the ash. Most of these disposal sites lack the safeguards necessary to keep the waste from leaking out, resulting in higher risks that nearby communities may be subject to contamination or even large-scale disasters.

Coal ash: a deadly problem

Coal ash is generated at coal-fired power plants across the US and is the second largest industrial waste stream in the country. Coal ash contains high levels of toxic heavy metals, including arsenic, lead and selenium. Many of these heavy metals are capable of causing cancer, thereby threatening the health of not just the environment but the human population. In addition to the risk of cancer, unsafe coal ash dumping may also lead to learning disabilities, neurological disorders, birth defects, reproductive failure, asthma and other illnesses. The toxins found in coal ash have been linked to organ disease, cancer, respiratory illness, neurological damage and developmental problems.

According to the United States Environmental Protection Agency (EPA), at least 535 coal ash ponds operate without a simple liner to prevent toxic chemicals and heavy metals from leaching into the ground and nearby water sources. People who live within one mile of unlined coal ash storage ponds can have a one in 50 risk of cancer – more than 2000 times higher than what the EPA considers acceptable. According to an EPA risk assessment, living near a wet coal ash storage pond is more dangerous to a person’s health than smoking a pack of cigarettes a day.

Coal ash generally contains arsenic, lead, mercury and selenium, as well as aluminum, barium, boron and chlorine, all of which can be toxic and can cause cancer, heart damage, lung disease, respiratory distress, kidney disease, reproductive issues, gastrointestinal illness and birth defects – especially in cases of prolonged exposure. Exposure to toxic coal ash can lower birth rates, cause tissue disease, slow development and even kill plants and animals, radically affecting the ecosystem. Coal ash pollution builds up in animals and plants, slowly making its way up the food chain through consumption. Children are most susceptible to the potential negative health impacts of coal ash, and the EPA estimates that 1.54 million children live near coal ash storage sites.

There are 1425 coal ash ponds and landfills in 37 states, and in many storage ponds and pits, the waste has slowly seeped out, poisoning water supplies, damaging ecosystems and threatening the health of citizens. In July 2007, the EPA identified 63 sites in 23 states where coal ash has contaminated groundwater and harmed the local ecosystem.

Providing a solution: recycling coal ash in the construction industry

In 2013, 51.4 million short t of coal ash were processed and recycled into concrete, wallboard and other materials. The remainder languishes in more than 650 open-air ponds and landfills. The amount of coal ash used in concrete has increased in the past five years, but the majority still remains in dangerous wet storage. Industry representatives estimate that 43% of coal ash is currently recycled into construction materials, which leaves more than 70 million short t of ash to be dumped into pits and landfills.

Up until the end of 2014, coal ash fell under the Resource Conservation and Recovery Act (RCRA) of 1976 but was classified as “exempt waste”, leaving states to decide what to do with the millions of short tons of coal ash generated each year.

On 19 December 2014, the EPA announced the first-ever federal regulations for the disposal of coal ash, classifying it as equivalent to everyday trash. Under the EPA’s final rule, new and existing coal ash storage ponds and landfills will face a variety of requirements, including routine groundwater monitoring and protective liners for all new units.

Worldwide Recycling Equipment Sales LLC can supply thermal desorption units through our Vulcan® Systems. Vulcan® Thermal Desorption Units can be used to remove contaminates like mercury and to reduce carbon content, making coal ash suitable for beneficial reuse in concrete or cement kilns.

In addition to providing thermal desorption equipment to process coal ash, Vulcan Systems also offers drying equipment for other types of ash and a variety of other materials. Its Vulcan® Fly Ash Drying System consists of a 48 in. long x 9 in. dia. rotary drum and is powered by four 50 hp, 208/230/460 V, 3-phase electric motors. This unit comes equipped with a 72 000 ft3/min. pulse jet baghouse and includes two compressed air tanks for pulse jet cleaning. During the process, fly ash is fed into the rotary dryer. After passing through the dryer, the dried material is discharged to a transfer conveyor for further sorting and separation. The vapor from the process is pulled through a cyclone that is specifically designed to deal with the fine dust, as well as a high-temperature baghouse, which removes all fine particulates from the vapor stream.

Conclusion

The reuse of coal ash protects air and water, as well as lowers greenhouse gas emissions by reducing carbon inputs into cement. Through the beneficial reuse of coal ash, spills from wet storage ponds and contamination of the soil and water can be avoided.

Vulcan® Systems custom-designs and manufactures drying, calcining and thermal desorption equipment. Each system is custom-built to suit the client’s specific needs. Its services include setup, commissioning, training and maintenance support services over the lifetime of a project.